1. Field
The present general inventive concept relates to an apparatus and a method of locating a moving robot, and more particularly to an apparatus to detect a position of a moving robot using a distance sensor that senses an obstacle.
2. Description of the Related Art
A movable robot such as a robot cleaner must be able to recognize a correct position. Conventional robots have been using an absolute navigation method combined with a dead reckoning (DR) method in recognizing position. The absolute navigation includes a method of attaching a radio frequency identification (RFID) or an absolute positioning mark to a certain fixed position, and a method using a global positioning system (GPS). In case of DR, the position can be detected by obtaining a rotational velocity and a straight advance velocity using an encoder sensor mounted to a wheel of the robot and performing integral calculus with the obtained velocity values. Additionally, DR includes a method that doubly performs integral calculus with an acceleration value obtained from an acceleration sensor, and a method that performs integral calculus with a rotational velocity which is an output of a gyro sensor. Although the DR methods are very precise, since the position value results from integral calculus, an error is increased as a running distance of the robot and the number of rotations are increased.
Often, robots mounted with wheels use an inertial navigation method that uses an encoder sensor and a gyro sensor, because these sensors are advantageous in terms of precision and low cost. However, with the inertial navigation, errors are accumulated and furthermore the error, once generated, cannot be easily compensated. Although an inertial error can be compensated for by a GPS sensor monitoring the robot from the outdoors, the GPS sensor is unavailable indoors or in the center of a city having the possibility of multiple paths. Though there is another sensor which applies trigonometry, this is not desirable because a dedicated attachment is required. Also, a simultaneous localization and map building (SLAM) method has been widely used, which simultaneously performs position detection of the robot and drawing of a map. However, the SLAM method is disadvantageous because an expensive camera and scan sensor are required.